The encapsulation of components within vehicles is well-known for retaining heat and noise. Absorbing powertrain radiated noise may be achieved via the incorporation of insulating materials applied to the external surface of the transmission to provide an operating temperature that reduces gearbox friction and enables more efficient re-start of the vehicle.
Component encapsulation effectively retains heat within the gearbox structure, gearbox components and its lubrication system to reduce the viscosity and density of gearbox oil for the purpose of reducing friction and improving efficiency.
Current approaches include close-fitted thermal encapsulation and tunnel mounted encapsulation. Close-fitted thermal encapsulation comprises several parts that are fixed to the transmission in a skin-like manner, which means that this type of encapsulation does not let heat flow out and therefore leads to extra heat in the cooling system. Tunnel mounted encapsulation uses a gearbox body mounted cover; consequently the noise radiated from the gearbox is attenuated by the encapsulation and therefore Noise, Vibration & Hardness (NVH) within the vehicle is reduced. However, this type of encapsulation, while providing a benefit through raised oil temperatures and friction reduction, can also provide a challenge for heat rejection, for example, in hot climates. Such situations can also exist with close-fitted encapsulation and manual transmissions where excessive oil temperatures can limit the amount of encapsulation applied. Therefore there is scope for improvement on current approaches.
The present invention has been devised to mitigate or overcome at least some of the above-mentioned problems.